System Parameters, Transit Times, and Secondary Eclipse Constraints of the Exoplanet Systems Hat-P-4, Tres-2, Tres-3, and Wasp-3 from the Nasa EPOXI Mission of Opportunity

Abstract

As part of the NASA EPOXI Mission of Opportunity, we observed seven known transiting extrasolar planet systems in order to construct time series photometry of extremely high phase coverage and precision. Here we present the results for four "hot-Jupiter systems" with near-solar stars—HAT-P-4, TrES-3, TrES-2, and WASP-3. We observe 10 transits of HAT-P-4, estimating the planet radius R[subscript p] = 1.332 ± 0.052 R [subscript Jup], the stellar radius R [subscript ★]= 1.602 ± 0.061 R [subscript ☉], the inclination i = 89.67 ± 0.30 deg, and the transit duration from first to fourth contact τ = 255.6 ± 1.9 minutes. For TrES-3, we observe seven transits and find R[subscript p] = 1.320 ± 0.057 R [subscript Jup], R [subscript ★] = 0.817 ± 0.022 R [subscript ☉], i = 81.99 ± 0.30 deg, and τ = 81.9 ± 1.1 minutes. We also note a long-term variability in the TrES-3 light curve, which may be due to star spots. We observe nine transits of TrES-2 and find R[subscript p] = 1.169 ± 0.034 R [subscript Jup], R [subscript ★] = 0.940 ± 0.026 R [subscript ☉], i = 84.15 ± 0.16 deg, and τ = 107.3 ± 1.1 minutes. Finally, we observe eight transits of WASP-3, finding R[subscript p] = 1.385 ± 0.060 R [subscript Jup], R [subscript ★] = 1.354 ± 0.056 R [subscript ☉], i = 84.22 ± 0.81 deg, and τ = 167.3 ± 1.3 minutes. We present refined orbital periods and times of transit for each target. We state 95% confidence upper limits on the secondary eclipse depths in our broadband visible bandpass centered on 650 nm. These limits are 0.073% for HAT-P-4, 0.062% for TrES-3, 0.16% for TrES-2, and 0.11% for WASP-3. We combine the TrES-3 secondary eclipse information with the existing published data and confirm that the atmosphere likely does not have a temperature inversion.